Hours later, the elementary school principal was found handcuffed to a tree about a mile and half east of the school.

"Franklin Floyd and Michael left, never to be seen again for a long time," Whetsel said.

Floyd was later arrested but would never say what happened to Michael. In a NewsChannel 4 interview from 1995, Whetsel said Floyd was the key to finding Michael.

"Until Floyd opens his mouth and lets us know where Michael's at, it's going to be almost impossible to locate him," Whetsel said.

For years, it has been a mystery investigators couldn't solve. Last summer, an FBI agent went to interview Floyd and asked about Michael. According to the FBI, it was during that interview Floyd confessed. He told the agent he shot Michael twice in the back of the head.

He then told the agent he buried the boy near the last exit leaving Oklahoma and heading into Texas. A search was done of the area, but no evidence was ever found.

"When Michael took his last breath here on Earth, he took the very next breath in Jesus' arms," said Merle Bean, Michael's foster-mother.

At the time of his abduction, Michael was in state custody. He was living with Merle and Ernest Bean. The couple was unable to meet us for an interview but spoke to us by phone. They said they are grateful for the prayers of so many Oklahomans.

"I feel like there is closure, and this is just where I want it to end," Merle said.

The sheriff agrees, even though he wishes Michael could have been found alive. "It's not easy to accept, but at least it's nice to know what happened," Whetsel said.

The FBI investigator who has worked this case said he hopes to interview Floyd again soon.

That agent said he thinks Floyd may have answers which could help solve other cases, including what really happened to Michael's mother.

The boy's mother died in 1990, and investigators believe Floyd may have details about what really happened to her.

Other notable cold cases in United States history:

11PHOTOS

Notable cold cases and unsolved murders throughout history

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Man confesses to killing missing Oklahoma boy more than 20 years ago​

In June 1893 Lizzie Borden stood trial, later acquitted, for killing her father and stepmother with an ax.

(Photo via Bettmann/Getty Images)

Foreboding Kingsbury Run, shunned by the timid as the legend of its murders has grown, is indicated on this map by dots locating 10 of the 11 torso murders which have occurred there since Sept. 23, 1935. Police, delving into the lives of the mad murderer's victims, hope to uncover clues which will end the periodic killings. Discovery of photo negatives in the belongings of Edward Andra Ssy, first victim, show Andra Ssy in a strange room which, if identified, may provide a live lead, police believe. As the map shows, the murderer departed only twice from his custom of assailing victims in Kingsbury Run or adjacent Cuyahoga river valley.

(Bettmann via Getty Images)

Bucks Row, now Durward Street, east London, where the body of Mary Ann Nichols, victim of Jack the Ripper, was found lying across the gutter.

U.S. labor leader Jimmy Hoffa is photographed at the Greater Pittsburgh Airport, Pennsylvania in this April 12, 1971 file photograph. Hoffa was switching planes from San Francisco, and was returning to the federal prison in Allenwood, Pennsylvania. Hoffa was let out of prison to visit his wife, who had been hospitalized with heart problems. FBI teams on May 25, 2006 sifted by hand through dirt from a chest-deep hole in the ground in an intense search for the body of Jimmy Hoffa three decades after his disappearance. Hoffa was last seen outside a Detroit-area restaurant where he was to meet New Jersey Teamsters' boss Anthony "Tony Pro" Provenzano, a member of the Genovese crime family, and a local Mafia captain, Anthony "Tony Jack" Giacalone. Hoffa was declared dead in 1982, and numerous books about his life have pinned his disappearance on mobsters who murdered him because they did not want him interfering with their close ties to the union.

(REUTERS/Jerry Siskind)

The site where 6 year old JonBenet Ramsey was killed in Boulder, Colorado, 1996.

Los Angeles Police detectives released this composite drawing March 27 of the man they believe killed rap star Notorious B.I.G. in Los Angeles recently. The suspect, a black man in his early 20's with close-cropped hair, was wearing a bow-tie the night of the drive-by killing. Investigators have set up a toll free number for the public to call with any information about the suspect.
NOTORIOUS BIG

Donna Norris poses next to a photo of her daughter Amber Hagerman, January 4, 2011, who was kidnapped 15 years ago while riding a bicycle near Norris mother's home in Arlington, Texas on January 13, 1996. (Richard W. Rodriguez/Fort Worth Star-Telegram/MCT via Getty Images)